PROJECT SUMMARY Achieving high rates of retention in human immunodeficiency (HIV) care and viral suppression through antiretroviral therapy not only reduces mortality, but also is a means to reduce the incidence of HIV in affected communities because viral suppression greatly decreases communicability and prevents the transmission of resistant strains of the virus. Retention in care and viral suppression have been particularly challenging for minority populations leading to racial and ethnic disparities in HIV outcomes, including survival. Among people living with HIV infection in 2013, the percentage that was virally suppressed was only 51.5% among African Americans, 58.2% among Latinos, and 65.0% among whites. Our central hypothesis is that provider patient- centered care (PCC) factors interacting with dynamic patient psychosocial factors as well as neighborhood social determinants and medical case management site factors are influencing retention in care and viral suppression and thus contributing to health disparities. The objective of this application is to identify provider PCC factors that are moderating the effect of changes in individual characteristics on retention in care and viral suppression while considering neighborhood social determinants and medical case management site factors and to predict to what extent changes in PCC factors could improve HIV care retention and viral suppression and thus reduce health disparities. We will accomplish these objectives with a cohort study of people enrolled in the Miami-Dade County Ryan White Program 2019?2021. The Ryan White Program serves 52% of people living with HIV in the United States, in particular the medically underserved. To test our central hypothesis and achieve the objectives of this application, we propose the following four specific aims: 1) Using causal Bayesian networks, assess the moderating role of HIV provider PCC factors on the association between patient-level characteristics and retention in HIV care, viral suppression, and related health disparities cross- sectionally while accounting for neighborhood-level and medical case management site factors; 2) By means of dynamic causal Bayesian networks, assess the moderating role of HIV provider PCC factors on the association between longitudinal changes in patient-level characteristics and changes in retention in HIV care, viral suppression, and related health disparities; 3) Using dynamic causal Bayesian networks, estimate the magnitude of the expected improvement in retention in HIV care, viral suppression, and related health disparities, produced by changing provider PCC factors; and 4) Identify feasibility and acceptability issues related to potential interventions to address the most influential health disparities factors identified in aims 1?3 using expert interviews and focus group discussions with RWP providers, administrators, and patients. This research thus supports one of the Trans-NIH Plan for HIV-Related Research ?cross-cutting? priorities to reduce disparities in treatment outcomes.